[Buildroot] [git commit] Makefile: don't hang the build if there are no file lists

[Yann E. MORIN]

commit: https://git.buildroot.net/buildroot/commit/?id=aa1e74745c93534a14981616b92956e920a01dc5
branch: https://git.buildroot.net/buildroot/commit/?id=refs/heads/master

In very limited configurations, it is possible to have a case where no
.files-list-staging.txt files are created. In this case:

    cat $(sort $(wildcard $(BUILD_DIR)/*/.files-list-staging.txt)) > \
        $(BUILD_DIR)/packages-file-list-staging.txt

becomes:

    cat > \
        $(BUILD_DIR)/packages-file-list-staging.txt

which of course makes the build hang.. forever.

So we fix this by checking the list is not empty. To keep the code
readable, we introduce an intermediate variable to store the list of
these files.

Signed-off-by: Thomas Petazzoni <thomas.petazzoni at bootlin.com>
Signed-off-by: Thomas De Schampheleire <thomas.de_schampheleire at nokia.com>
[yann.morin.1998 at free.fr: always create the file, even if empty]
Signed-off-by: Yann E. MORIN <yann.morin.1998 at free.fr>
---
 Makefile | 16 ++++++++++------
 1 file changed, 10 insertions(+), 6 deletions(-)

diff --git a/Makefile b/Makefile
index 5455e6662e..156ceb9aae 100644
--- a/Makefile
+++ b/Makefile
@@ -728,6 +728,10 @@ $(TARGETS_ROOTFS): target-finalize
 # Avoid the rootfs name leaking down the dependency chain
 target-finalize: ROOTFS=
 
+TARGET_DIR_FILES_LISTS = $(sort $(wildcard $(BUILD_DIR)/*/.files-list.txt))
+HOST_DIR_FILES_LISTS = $(sort $(wildcard $(BUILD_DIR)/*/.files-list-host.txt))
+STAGING_DIR_FILES_LISTS = $(sort $(wildcard $(BUILD_DIR)/*/.files-list-staging.txt))
+
 .PHONY: host-finalize
 host-finalize: $(PACKAGES) $(HOST_DIR) $(HOST_DIR_SYMLINK)
 	@$(call MESSAGE,"Finalizing host directory")
@@ -808,12 +812,12 @@ endif # merged /usr
 
 	touch $(TARGET_DIR)/usr
 
-	cat $(sort $(wildcard $(BUILD_DIR)/*/.files-list.txt)) > \
-		$(BUILD_DIR)/packages-file-list.txt
-	cat $(sort $(wildcard $(BUILD_DIR)/*/.files-list-host.txt)) > \
-		$(BUILD_DIR)/packages-file-list-host.txt
-	cat $(sort $(wildcard $(BUILD_DIR)/*/.files-list-staging.txt)) > \
-		$(BUILD_DIR)/packages-file-list-staging.txt
+	$(if $(TARGET_DIR_FILES_LISTS), \
+		cat $(TARGET_DIR_FILES_LISTS)) > $(BUILD_DIR)/packages-file-list.txt
+	$(if $(HOST_DIR_FILES_LISTS), \
+		cat $(HOST_DIR_FILES_LISTS)) > $(BUILD_DIR)/packages-file-list-host.txt
+	$(if $(STAGING_DIR_FILES_LISTS), \
+		cat $(STAGING_DIR_FILES_LISTS)) > $(BUILD_DIR)/packages-file-list-staging.txt
 
 .PHONY: target-post-image
 target-post-image: $(TARGETS_ROOTFS) target-finalize staging-finalize